1. Field of the Invention
This invention relates to an electric circuit for controlling vertical movement of a pole antenna provided on a vehicle body as an antenna for a vehicle-mounted radio receiver.
2. Description of the Prior Art
The pole antenna of the type described is preferably of such an arrangement that a control circuit is formed to vertically move the antenna whenever necessary and the antenna is lowered and housed in a vehicle body when the vehicle is stopped, so that breaking of the pole antenna out of fun during the stop of the vehicle can be avoided and the antenna can stay out of the way of people or objects being therearound.
Heretofore, there has been proposed a circuit shown in FIG. 1 as a circuit to satisfy the requirements as described above. Description will hereunder be given of the proposed circuit with reference to FIG. 1.
A contact 43 of a switch 4 for raising the antenna and a contact 53 of a switch 5 for lowering the antenna are connected to a positive pole of a power source 1. Further, a contact 42 of the switch 4 for raising the antenna is connected to a negative pole of the power source 1 through a limit switch 9 at the raising side and a contact 52 of the switch 5 for lowering the antenna is also connected to the negative pole of the power source 1 through a limit switch 10 at the lowering side. Furthermore, a contact 41 of the switch 4 for raising the antenna is connected to one end of a reversible motor 3, and a contact 51 of the switch 5 for lowering the antenna is connected to the other end of the motor 3 through a relay 6. A contact 44 of the switch 4 for raising the antenna and another contact 45 of the switch 5 for lowering the antenna, when not operated, are in contact with the contacts 43 and 53, respectively. The limit switch 9 at the raising side is turned off at a position of completion of raising of the antenna in accordance with a rotated position of the motor 3, and turned on in any position other than the above. Likewise, the limit switch 10 at the lowering side is turned off at a position of completion of lowering of the antenna and turned on at any position other than the above. Furthermore, a contact 21 of an ignition switch 2 is connected to the positive pole of the power source 1, a contact 22 contacting a contact 24 at an ACC position and an IG position, both of which are "on" positions, is connected to a coil 61 of a relay 6 through a diode 8, and a contact 23 contacting the contact 24 at an IG position and a ST position, both of which are "on" positions, is connected to the coil 61 of the relay 6 through a diode 7, respectively, and the coil 61 is further connected to the negative pole of the power source 1. A contact 62 of a switch 66 of the relay 6 is connected to the other end of the motor 3, a contact 63 to the limit switch 10, a contact 64 to the contact 51 of the switch 5 for lowering the antenna, respectively, a contact 65 contacts the contact 64 when the coil 61 is energized, and normally contacts the contact 63.
With the abovedescribed circuit arrangement, if the contact 24 of the ignition switch 2 is brought to the ACC, IG or ST position, each of which is an "on" position, the coil 61 of the relay 6 is energized, the contact 65 of the switch 66 is brought into contact with the contact 64, and thereafter, the switch 4 for raising the antenna is operated to bring the contact 44 in contact with the contact 42, then the motor 3 can be rotated in a direction of raising the antenna, and the motor 3 continues to rotate until the switch 4 for raising the antenna is stopped in operation or the antenna has been raised up to turn the limit switch 9 off. If the switch 5 for lowering the antenna is operated, then the antenna can be likewise lowered. Additionally, if the contact 24 of the ignition switch 2 is brought to an "off" position under a condition where the antenna is in the raised position and the limit switch 10 is on, then the coil 61 of the relay 6 is deenergized, whereby the contact 65 contacts the contact 63 and the motor 3 is rotated in a direction of lowering the antenna regardless of operation of the switch 5 for lowering the antenna. When the limit switch 10 is turned off upon completion of lowering the antenna, the motor 3 is stopped in rotation.
The desired requirements are satisfied by the circuit shown in FIG. 1, however, while the ignition switch 2 is brought to the "on" position, the current continuously passes through the coil 61 of the relay 6. This current is of about 150 mA and is insignificant in value during rotation of the engine, i.e., power generation by a generator. However, such a disadvantage is presented that the vehicle-mounted power source 1, i.e., a battery may be overdischarged when the engine is stopped in operation. In short, this disadvantage is resulted from the fact that when an occupant of the vehicle brings the contact 24 of the ignition switch 2 to the ACC position to stop the engine in operation, and thereafter, listens in a vehicle-mounted radio, the current passes through the coil 61 of the relay 6 through the contact 22, whereby the discharge voltage from the battery increases.